Bunashimeji mushroom named ‘Marmo22go’

ABSTRACT

The present variety of mushroom named ‘Marmo22go’ was cultivated by the gathering and repeated breeding of Bunashimeji mushrooms having dominant traits, which has good qualitative character and appearance, a thick white stem, a large mushroom size, and a resistance to high temperatures. This edible mushroom is exquisite in stability, reproducibility and uniformity when being produced.

BACKGROUND OF THE INVENTION

This invention relates to a new and distinct variety of mushroom of Bunashimeji mushroom, Hypsizygus marmoreus (Peck) Bigelow. This new variety named ‘Marmo22go’ cultivated by repeated breeding of Bunashimeji mushrooms having dominant traits, which has a thick white stem, a large mushroom size, a resistance to high temperatures and ensures presentable stability, reproducibility and uniformity.

Bunashimeji (Hypsizygus marmoreus) now boasts of being the second most consumed edible mushroom after enokitake mushroom in Japan. After bunashimeji was cultivated and became available in the market in large quantities, ‘Hokuto 8gokin’ was developed which reduced the characteristic bitterness of the original bunashimeji. Investigation on tasty bunashimeji was continued even after the development of Hokuto 8gokin, and a variety with improved taste, quality and keeping quality named ‘Hokuto 18gokin’ was developed, which contributed to an increase in consumption.

In order to further improve cultivation stability and the quality of mushrooms, selective breeding was repeatedly carried out by cross-breeding. As a result, a ‘Marmo22go’ mushroom was developed with a thick white stem and larger mushroom size, and a greater resistance to high temperatures, as compared to the ‘Hokuto 18gokin’ mushroom. Subsequently, the stability, reproducibility and uniformity of the variety were verified, and cultivation was completed.

SUMMARY OF THE INVENTION

The present invention is a new and distinct variety of mushroom characterized particularly by its good qualitative character and appearance, a thick white stem, large mushroom size, and a resistance to high temperatures, which can be cultivated by gathering and repeated breeding of fungal strains having dominant traits and is exquisite in stability, reproducibility and uniformity when being produced. This novel and distinct variety of mushroom is identified as ‘Marmo22go’.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a phylogenetic tree illustrating the antecedents of ‘Marmo22go’.

FIGS. 2A and 2B respectively show front and back images of a dual-culture of ‘Marmo22go’ colony.

FIGS. 3A and 3B respectively show front and back images of a dual-culture of ‘Marmo22go’ and ‘Marmo23go’.

FIGS. 4A and 4B respectively show front and back images of a dual-culture of ‘Marmo22go’ and ‘Hokuto 18gokin’.

FIGS. 5A and 5B respectively show front and back images of fungal flora of ‘Marmo22go’.

FIGS. 6A and 6B respectively show front and back images of fungal flora of ‘Marmo23go’.

FIGS. 7A and 7B respectively show front and back images of fungal flora of ‘Hokuto 18gokin’.

FIG. 8 shows an image of a fruit body of ‘Marmo22go’.

FIG. 9 shows an image of a fruit body of ‘Marmo23go’.

FIG. 10 shows an image of a fruit body of ‘Hokuto 18gokin’.

FIG. 11 shows an image of size of mottle of ‘Marmo22go’.

FIG. 12 shows an image of size of mottle of ‘Marmo23go’.

FIG. 13 shows an image of size of mottle of ‘Hokuto 18gokin’.

FIG. 14 shows an image of shape, length and size of stipe of ‘Marmo22go’.

FIG. 15 shows an image of shape, length and size of stipe of ‘Marmo23go’.

FIG. 16 shows an image of shape, length and size of stipe of ‘Hokuto 18gokin’.

FIGS. 17A and 17B respectively show front and back images of a dual-culture of ‘Marmo22go’ and ‘MH025615’.

FIGS. 18A and 18B respectively show front and back images of a dual-culture of ‘Marmo22go’ and ‘MH025616’.

DETAILED DESCRIPTION OF THE INVENTION

The history of the ‘Marmo22go’ mushroom in terms of improvement period and the like are set forth in the following chronological list of each stage of variety improvement:

May 2005: Cultivation of ‘MH025616’ strain.

December 2014: Cultivation of ‘MH025615’ strain.

January 2017: ‘MH025616’ and ‘MH025615’ strains were crossed, and of the obtained strains, a strain of high quality, of the targeted white stem was selected and designated ‘MH025617’. Growing test was repeatedly conducted on ‘MH025617’ and since distinguishability, stability and uniformity were confirmed, the strain was named ‘Marmo22go’ and cultivation was completed. Dual culture performed for ‘Marmo22go’ and ‘MH025615’ and dual culture performed for ‘Marmo22go’ and ‘MH025616’ showed formation of a zone line (FIGS. 17A, 17B, 18A, and 18B).

March 2018: Applied for registration of a new variety to the Ministry of Agriculture, Forestry and Fisheries of Japan.

The above crossing is summarized in the phylogenetic tree illustrated in FIG. 1.

The ‘Marmo22go’ mushroom has the following characteristics: a thick white stem, a large mushroom size, and a resistance to high temperatures.

(1) Comparison with existing variety by dual culture

Dual culture was performed for the ‘Marmo22go’ mushroom and similar varieties so as to examine whether or not a zone line is formed.

-   Study method: As an examination method, a potato dextrose agar     medium was used, and the ‘Marmo22go’ mushroom and similar varieties     were inoculated thereon face to face at an interval of 3 cm, and     then culture was performed at 25° C. for 28 days to examine whether     or not a zone line was formed. -   Strain used:     -   -   ‘Marmo22go’.—Present variety.         -   ‘Marmo23go’.—Variety similar to the present variety.         -   ‘Hokuto18gokin’.—Variety similar to the present variety. -   Results: Zone lines were formed between ‘Marmo22go’ and all other     co-cultured varieties (Table 1, FIGS. 2 to 4). This clearly shows     that the present mushroom is a new variety.

TABLE 1 Results of dual culture Similar varieties Marmo23go strain Hokuto 18gokin Marmo22go + + + is present and − is absent. *Zone line formation was not observed in the dual culture between ‘Marmo22go’ strains. (2) Culture characteristics of ‘Marmo22go’

-   Study method: After inoculating an agar piece of the ‘Marmo22go’     having a diameter of 5 mm in potato dextrose agar, preculture was     performed at 25° C. for 4 days and hyphae were regenerated (about 10     mm in diameter), and then culture was performed for 7 days at     intervals of 5° C. between 5° C. and 30° C. When the average daily     hyphae growth rate was calculated based on a hyphae growth rate for     seven days of the culture, it was found that the average hyphae     growth rate of ‘Marmo22go’ was the fastest at 25° C. (See Table 2).     Further, it was found that the hyphae growth rate of ‘Marmo22go’ was     faster than that of ‘Marmo23go’ and ‘Hokuto 18gokin’ at 30° C. (See     Table 2). ‘Marmo22go’ was asexually reproduced by inoculating on a     potato dextrose agar at Mushroom Research Laboratory of the Hokuto     Corporation in Nagano-shi, Nagano, Japan.     (3) Morphological characteristics of the ‘Marmo22go’ mushroom in a     cultivation example -   Cultivation method:     -   -   Container.—An 850 polypropylene bottle (Capacity: 850 ml,             diameter 58 mm) was used.         -   Culture medium.—Conifer sawdust, corn cob, rice bran and             wheat bran were mixed at the dry weight ratio of 7:3:8:2,             and the water content was adjusted to 65%. The culture             medium was filled up to the brim of the bottle at the rate             of 540±20 g per bottle, and was sterilized at high pressure.         -   Starter culture.—About 20 mL of sawdust starter cultures per             bottle was inoculated.         -   Culture.—Culture was performed at 22° C. for 50 to 90 days             at 70% moisture.         -   Growth.—After completing the culture, the inoculum is             removed, and shifted to a growing room. Development was             conducted under a temperature of 15±1° C., at humidity of             95% or more, without exposure to light particularly in the             first 14 days, then after the 14th day, 500-1,000 Lx is             taken and development is conducted at about 2,000 ppm CO₂             density. The mushroom is harvested when the cap in the             center of the stump has sufficiently opened. -   Cultivation results: Table 2 shows the characteristics of the     ‘Marmo22go’ and specific difference in characteristics as compared     with the similar varieties when culture was performed under the     abovementioned conditions. Also, the whole images of the respective     fruit bodies, the images of the respective mottles, and the images     of the respective stipes have also been attached. (Refer to FIGS. 8     to 16).

TABLE 2 Fungus characteristics Table of Hypsizygus marmoreus (Peck) Bigelow of Recording and Registration Present Similar variety variety Hokuto Marmo22go Marmo23go 18gokin Physiological property Dual culture Zone line formation observed observed observed Dislike-touch reaction — — — Density of hyphae dense dense medium Mycelial growth dense dense medium Color of surface of colony white white white Color of back of colony pale yellow pale yellow pale yellow Accommodativeness for temperature Optimal temperature for 24° C. 24° C. 24° C. hyphal growth (° C.) Hyphal growth rate 5° C./mm 0.72 mm 0.58 mm 0.78 mm 10° C./mm 1.37 mm 1.38 mm 1.42 mm 15° C./mm 2.28 mm 1.99 mm 2.33 mm 20° C./mm 3.49 mm 3.00 mm 3.44 mm 25° C./mm 3.96 mm 3.20 mm 3.65 mm 30° C./mm 3.02 mm 2.34 mm 1.61 mm Morphological property Cap Cross sectional shape rounding rounding rounding mound mound mound Mottle of the surface medium medium medium Size of mottle small small medium Distribution of mottle whole whole whole Clarity of mottle very clear very clear very clear Size (diameter) 19.8 mm 19.7 mm 18.8 mm Color of central area grey- grey- grey- brown brown brown 199C 199A 199B Color of peripheral area grey- grey- grey- brown brown brown 199D 199B 199C Thickness (mm) 8.9 mm 8.7 mm 8.2 mm Fleshy medium medium medium Gill Color yellow- yellow- yellow- white white white 158C 158C 158C Alignment crinkle crinkle crinkle Width medium medium medium Density medium medium medium Stipe Shape medium long and medium thick thin thick Length 49.3 mm 55.7 mm 46.2 mm Size (diameter) 12.6 mm 10.2 mm 9.5 mm Color white white white 155B 155B 155B Hair absent absent absent Fleshy medium medium medium Ratio of maximum diameter of 1.61 mm 1.68 mm 1.55 mm stem to diameter just below cap Cultural property Development of fruit body Development strain strain strain Optimal culture period 70 days 90 days 90 days Length of time from fruit 21.4 days 21.1 days 21.8 days body-formation promotion to fruit body harvesting at optimal temperature Optimal temperature for 15° C. 15° C. 15° C. primordial development Optimal temperature for fruit 15° C. 15° C. 15° C. body growth Yield Yield of fruit body 133.8 g 123.1 g 117.6 g The number of productive stem 32.8 37.6 40.8 *The employed color chart is R.H.S. Colour Chart, 2007, Fifth edition, prescribed by Royal Horticultural Society, England. 

What is claimed is:
 1. A new, distinct variety of Bunashimeji mushroom as substantially illustrated and described in the specification. 